Anal sacs, also known as ‘anal glands’, are a topic of discussion not for the weak stomached! Most dogs go through their entire lifetime without having any problems with their anal glands (if this is your dog then thank yourself lucky!). However, anal sac issues are much more common than you may think and Vets and Nurses are presented with anal gland problems in dogs every single day. This article will dive into the horrifying world of anal sac diseases and will discuss what they actually are and how to recognise a problem.

What are anal sacs?

Anal sacs are two small oval-shaped pouches located internally at each side of the anus. I usually describe them as being in the 4 and 7 o‘clock position on a clock face. Anal glands produce a foul smelling fluid (often described as a fishy smell!) that is unique to each individual. It is believed that the fluid is expressed as part of a dog’s territorial or scent marking behaviour. The fluid is usually expressed from the anal glands when your dog passes a normal stool. Sometimes, dogs can also express their anal glands during times of stress or fear. 

Dogs, cats and other mammals have anal sacs, but humans do not have them…which is something that I am very happy about.

Common problems

Non-neoplastic or non-cancerous anal sac disorders (ASD’s) are seen in a large population of dogs. Despite anal gland problems being highly prevalent in general practice, some areas of anal gland issues still remain a mystery and there is little supportive evidence into the management of such conditions. 

Below lists some of the common anal gland conditions (this list is not exhaustive):

Anal sac impaction, also known as anal sacculitis 

If you dog does not naturally empty their anal sacs then their anal sacs can become full of fluid. When the anal glands are not fully emptied this can lead to anal gland impaction because the fluid inside becomes dry and creates an obstruction to the drainage of the sac. This condition is usually managed by a trip to the Vets who will attempt to manually empty the anal glands with their fingers.

Anal sac abscesses 

When anal glands become impacted and are not emptied, the fluid contents can turn into an infection and this can lead to an abscess. Anal sac abscesses can be painful and the ‘pus-filled’ anal gland can burst out through the skin. Your Vet will usually prescribe anti-inflammatory medications and a course of antibiotics. 


An anal sac adenocarcinoma is the most common malignant primary tumour that arises from the anal sac. Sometimes this tumour only grows in the anal gland, other times it may spread and metastasise to the local lymph nodes or elsewhere in the body. There are a handful of factors which will therefore determine the management plan for this condition.

If your dog experiences repeated anal gland issues or there is an anal gland tumour, your Vet may consider flushing the anal glands or an anal sacculectomy procedure. Anal sacculectomy is the surgical removal of the anal sacs under general anaesthesia. This surgery is not complication free and can sometimes lead to faecal incontinence. However, it can also stop a malignant cancer from spreading if done early enough.

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How do I know if my dog’s anal sacs are causing a problem?

There are some classical clinical signs associated with anal gland problems, below lists some of the more common things you may see (this list is not exhaustive):

  • Scooting or dragging their bum along the floor
  • Excessive licking/chewing their hind feet or around their tail base
  • Pain when touched around the anus or tail base
  • Visible swellings at the side of the anus
  • Difficulty or pain during defecation
  • A very foul or fishy odour
  • Sitting down more frequently

Are there any dog breeds which are predisposed?

Yes! There are strong breed predispositions, research and evidence to suggest that certain types of dogs are more prone to anal sac diseases than others. Breeds such as Cavalier king Charles spaniels and cockapoos are over represented (O’Neill et al, 2021). From a clinical perspective, I see more anal gland problems in smaller breed dogs than larger breed dogs.

There can be multiple reasons that your dog develops anal gland problems and I won’t expand too far into this, but some causative factors may include: anatomical, lack of dietary fibre, incorrect nutrition, breed predispositions, genetics and allergies.

Interestingly, brachycephalic breeds and overweight dogs also have a greater prevalence of anal gland impaction (O’Neill et al, 2020). The link between obesity and anal sac problems is likely associated with their anal sacs not being able to empty as well, due to anatomy or lack of muscle tone.


To conclude, I hope that this article has summarised the foundations of anal sac diseases in dogs. If you do notice any of the associated clinical signs in your dog at home or are concerned your dog may be affected by their anal glands, contact your local Veterinarian for further advice.

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